1. Field of the Invention
The present invention relates to a communication control system and an information processing system, or more particularly, to a communication control system and information processing system based on table retrieval for retrieving a status transition table specifying protocols and information processing procedures.
2. Description of the Related Art
In a communication control system, complex status transition has been executed to follow a protocol based on a recommendation standardized as an international standard in the past. A popular method of executing status transition at a high speed has been described, for example, in Japanese Patent Laid-Open No. 64-65653. The protocol is proceeded as follows:
(a) frames are received from a remote station, PA1 (b) the frames are classified, and event numbers are created according to the contents, PA1 (c) status transition is executed according to an event number and a current state number, then a processing number to be executed next and a next state number to which control passes are retrieved, then PA1 (d) processing is executed according to a protocol associated with the calculated processing number.
In the above protocol, status transition is carried out as described below. That is to say, when a status transition table is retrieved, an address made up of an event number and a current state number (accessed at the start of table retrieval) is used to access the status transition table. Then, a next state number and processing number specified by this access are extracted from the status transition table. The next state number is used as a current state number for the next status transition. The processing number is used as an address of a corresponding processing program. By executing this process, a specific processing number and next state number are extracted from the status transition table according to an event number and a current state number.
However, according to the foregoing prior art, when an event number and a current state number are used as a set of input information, the set of input information yields only one processing number. Therefore, a set of input information cannot enable communication in association with multiple operation modes. This means that when a specific processing number is extracted according to an event number and a current state number, only one processing number is selected despite differences of operation modes.